Am I the only one who gets worse at building houses with each new sims game?

Your not the only one. I loved building houses in ts2. Especially bedrooms. I could spent hours building and it would turn out exactly how I wanted it. In ts3 I had problems building houses too big. There was just too much space and I felt like I had to fill every inch of it. The house shape always just turned in to a giant square/rectangle. The bathrooms were always way too big and I always had empty space I didn't know what to do with it. In ts4 I haven't even tried to build my own house yet. I just use the house already there or get one from the gallery. If I need to expand I will just use the premade rooms that are provided and switch them out as my families grew and changed.

I feel the complete opposite way, but I also understand your sentiment.
In a way there are a huge amount of complex build options in TS4 which can be overwhelming at times. Of course there are also things missing.

I never built in The Sim or The Sims 2. I only introduced myself to the latter a couple of months ago. Never played The sims.
I've always loved building structures in TS3 however, and for me the World Creation Tool is something I really, really miss in TS4. World building is one of my favorite things to do. In life haha. That level of customization not being available in the latest installment does actually annoy me at times, because I don't always want to move my sims into a pre-made world. I feel EA/Maxis is going to try and sell us as many pre-worlds as possible before we get our own little -create your own district- tool. If ever.

Another thing that very much bothers me in TS4 is the lack of ceilings tiles. This is where build mode truly falls short in my opinion. I love building old structures with wooden or dirty ceilings. None of that is possible, which for me can be immersion breaking because of that awful white space that's visible as soon as the camera tilts. And I tilt the camera a lot. My builds never feel complete due to the absence of proper ceiling textures.
I never understood the dev's choice not to include them, other than that it has to do with folks using the TS4 camera more and thus not seeing the ceilings. Other priorities too, obviously, but I'd appreciate it if they gave us that ceiling tool. As in, soon.

The ability to earth sculpt ponds and an additional stairs tool to create spiral stairs is something else I would like to see again.
Other than that I think TS4 build mode is the bees knees. It's my favorite so far!